/**************************************************************************/
/*                                                                        */
/*                                 OCaml                                  */
/*                                                                        */
/*          Manuel Serrano and Xavier Leroy, INRIA Rocquencourt           */
/*                                                                        */
/*   Copyright 2000 Institut National de Recherche en Informatique et     */
/*     en Automatique.                                                    */
/*                                                                        */
/*   All rights reserved.  This file is distributed under the terms of    */
/*   the GNU Lesser General Public License version 2.1, with the          */
/*   special exception on linking described in the file LICENSE.          */
/*                                                                        */
/**************************************************************************/

#define CAML_INTERNALS

#include <stddef.h>
#include "caml/alloc.h"
#include "caml/bigarray.h"
#include "caml/fail.h"
#include "caml/io.h"
#include "caml/mlvalues.h"
#include "caml/signals.h"
#include "caml/sys.h"
#include "caml/osdeps.h"
#include "caml/unixsupport.h"

#define Leave_blocking_and_uerror_if(e) \
  do { if (e) { \
         caml_leave_blocking_section(); \
         caml_win32_maperr(GetLastError()); \
         caml_uerror("map_file", Nothing); } } while(0)

/* Defined in [mmap_ba.c] */
extern value caml_unix_mapped_alloc(int, int, void *, intnat *);

CAMLprim value caml_unix_map_file(value vfd, value vkind, value vlayout,
                                  value vshared, value vdim, value vstart)
{
  HANDLE fd, fmap;
  int flags, major_dim, mode, perm;
  intnat num_dims;
  intnat dim[CAML_BA_MAX_NUM_DIMS];
  int64_t startpos, data_size;
  LARGE_INTEGER file_size;
  uintnat array_size, delta;
  void * addr;
  LARGE_INTEGER li;
  SYSTEM_INFO sysinfo;

  fd = Handle_val(vfd);
  flags = Caml_ba_kind_val(vkind) | Caml_ba_layout_val(vlayout);
  startpos = Int64_val(vstart);
  num_dims = Wosize_val(vdim);
  major_dim = flags & CAML_BA_FORTRAN_LAYOUT ? num_dims - 1 : 0;
  /* Extract dimensions from OCaml array */
  num_dims = Wosize_val(vdim);
  if (num_dims < 1 || num_dims > CAML_BA_MAX_NUM_DIMS)
    caml_invalid_argument("Unix.map_file: bad number of dimensions");
  for (intnat i = 0; i < num_dims; i++) {
    dim[i] = Long_val(Field(vdim, i));
    if (dim[i] == -1 && i == major_dim) continue;
    if (dim[i] < 0)
      caml_invalid_argument("Unix.map_file: negative dimension");
  }
  /* Determine file size */
  caml_enter_blocking_section();
  Leave_blocking_and_uerror_if(!GetFileSizeEx(fd, &file_size));
  /* Determine array size in bytes (or size of array without the major
     dimension if that dimension wasn't specified) */
  array_size = caml_ba_element_size[flags & CAML_BA_KIND_MASK];
  for (intnat i = 0; i < num_dims; i++)
    if (dim[i] != -1) array_size *= dim[i];
  /* Check if the first/last dimension is unknown */
  if (dim[major_dim] == -1) {
    /* Determine first/last dimension from file size */
    if (file_size.QuadPart < startpos) {
      caml_leave_blocking_section();
      caml_failwith("Unix.map_file: file position exceeds file size");
    }
    data_size = file_size.QuadPart - startpos;
    dim[major_dim] = (uintnat) (data_size / array_size);
    array_size = dim[major_dim] * array_size;
    if (array_size != data_size) {
      caml_leave_blocking_section();
      caml_failwith("Unix.map_file: file size doesn't match array dimensions");
    }
  }
  /* Create the file mapping */
  if (Bool_val(vshared)) {
    perm = PAGE_READWRITE;
    mode = FILE_MAP_WRITE;
  } else {
    perm = PAGE_READONLY;
    mode = FILE_MAP_COPY;
  }
  li.QuadPart = startpos + array_size;
  fmap = CreateFileMapping(fd, NULL, perm, li.HighPart, li.LowPart, NULL);
  Leave_blocking_and_uerror_if(fmap == NULL);
  /* Determine offset so that the mapping starts at the given file pos */
  GetSystemInfo(&sysinfo);
  delta = (uintnat) (startpos % sysinfo.dwAllocationGranularity);
  /* Map the mapping in memory */
  li.QuadPart = startpos - delta;
  addr =
    MapViewOfFile(fmap, mode, li.HighPart, li.LowPart, array_size + delta);
  Leave_blocking_and_uerror_if(addr == NULL);
  addr = (void *) ((uintnat) addr + delta);
  /* Close the file mapping */
  CloseHandle(fmap);
  caml_leave_blocking_section();
  /* Build and return the OCaml bigarray */
  return caml_unix_mapped_alloc(flags, num_dims, addr, dim);
}

CAMLprim value caml_unix_map_file_bytecode(value * argv, int argn)
{
  return caml_unix_map_file(argv[0], argv[1], argv[2],
                            argv[3], argv[4], argv[5]);
}

void caml_ba_unmap_file(void * addr, uintnat len)
{
  SYSTEM_INFO sysinfo;
  uintnat delta;

  GetSystemInfo(&sysinfo);
  delta = (uintnat) addr % sysinfo.dwAllocationGranularity;
  UnmapViewOfFile((void *)((uintnat)addr - delta));
}
